Response information transmission method, communications device, and network device

ABSTRACT

Example communication methods and apparatus are described. One example communication method includes receiving first indication information by a first communications device from a network device, where the first indication information indicates a first resource for sidelink communication. The first communications device sends the first data to a second communications device. The first communications device receives second indication information from the network device, where the second indication information is used to determine a second resource for transmitting feedback information. The first communications device receives feedback information of the first data from the second communications device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/856,251, filed on Apr. 23, 2020, which is a continuation ofInternational Application No. PCT/CN2018/106414, filed on Sep. 19, 2018.The International Application claims priority to Chinese PatentApplication No. 201711103677.8, filed on Nov. 10, 2017. All of theaforementioned applications are hereby incorporated by reference intheir entireties.

TECHNICAL FIELD

Embodiments of this application relate to communications systems, and inparticular, to a response information transmission method, a firstcommunications device, a second communications device, and a networkdevice.

BACKGROUND

Device-to-device (D2D) communication, vehicle-to-vehicle (V2V)communication, vehicle-to-pedestrian V2P (V2P) communication, orvehicle-to-infrastructure/network V2I/N (V2I/N) communication is atechnology for direct communication between terminal devices. V2V, V2P,and V2I/N are collectively referred to as V2X, namely, communicationbetween vehicles and anything.

Using the V2X communication as an example, the V2X communicationincludes a mode 3 and a mode 4. In the mode 3, a terminal deviceperforms control information and data communication with anotherterminal device on a time-frequency resource allocated by an accessnetwork device. In the mode 4, a terminal device autonomously selects atime-frequency resource and performs control information and datacommunication with another terminal device on the selectedtime-frequency resource. In conventional V2X communication, afterreceiving data, a receive-end terminal device does not feed back, tonotify the transmit-end terminal device whether the receive-end terminaldevice correctly receives the data, response information to atransmit-end terminal device that sends the data.

SUMMARY

Embodiments of this application provide a response informationtransmission method, a first communications device, a secondcommunications device, and a network device, to transmit responseinformation in V2X communication.

According to a first aspect, a response information sending method isprovided. The method includes: receiving, by a first communicationsdevice, first indication information from a network device, where thefirst indication information is used to indicate a first resource fortransmitting first data; sending, by the first communications device onthe first resource, the first data to a second communications device;receiving, by the first communications device, second indicationinformation from the network device, where the second indicationinformation is used to indicate a second resource for transmittingresponse information of the first data, and the second resource and thefirst resource do not include a same resource; and receiving, by thefirst communications device on the second resource, the responseinformation of the first data from the second communications device.

According to this embodiment of this application, the network deviceconfigures, for the first communications device and the secondcommunications device, the second resource that can be used for theresponse information. The first communications device and the secondcommunications device may transmit the response information on thesecond resource, and transmission of the response information isimplemented in V2X communication.

In a possible design, the first resource includes x subframes, where xis a positive integer, and the sending, by the first communicationsdevice on the first resource, the first data to a second communicationsdevice includes: sending, by the first communications device in asubframe n, the first data to the second communications device, wherethe subframe n belongs to the x subframes; and the second resourceincludes y subframes, where y is a positive integer, and the receiving,by the first communications device on the second resource, the responseinformation of the first data from the second communications deviceincludes: receiving, by the first communications device in a subframe m,the response information of the first data from the secondcommunications device, where the subframe m belongs to the y subframes,and the subframe m is a subframe, after a subframe n+k, with a minimumsequence number in the y subframes of the second resource, where thesubframe n+k is a k^(th) subframe after the subframe n, k is predefinedor is received by the first communications device from the networkdevice, and n, m, and k are all non-negative integers.

In a possible design, the subframe m includes a plurality of first timeunits, and the receiving, by the first communications device in asubframe m, the response information of the first data from the secondcommunications device includes: receiving, by the first communicationsdevice on one of the plurality of first time units included in thesubframe m, the response information of the first data from the secondcommunications device. Therefore, resource utilization efficiency can beimproved.

In a possible design, the receiving, by the first communications devicein a subframe m, the response information of the first data from thesecond communications device includes: receiving, by the firstcommunications device on some frequency domain resources in the subframem, the response information of the first data from the secondcommunications device. Therefore, resource utilization efficiency can beimproved.

In a possible design, the first indication information includes a firstbit map, and the second indication information includes a second bitmap.

According to a second aspect, a first communications device is provided.The first communications device includes: a receiving unit, configuredto receive first indication information from a network device, where thefirst indication information is used to indicate a first resource fortransmitting first data; and a sending unit, configured to send, on thefirst resource, the first data to a second communications device, wherethe receiving unit is further configured to receive second indicationinformation from the network device, where the second indicationinformation is used to indicate a second resource for transmittingresponse information of the first data, and the second resource and thefirst resource do not include a same resource; and the receiving unit isfurther configured to receive, on the second resource, the responseinformation of the first data from the second communications device.

According to this embodiment of this application, the network deviceconfigures, for the first communications device and the secondcommunications device, the second resource that can be used for theresponse information. The first communications device and the secondcommunications device may transmit the response information on thesecond resource, and transmission of the response information isimplemented in V2X communication.

In a possible design, the first resource includes x subframes, where xis a positive integer, and that the sending unit sends, on the firstresource, the first data to the second communications device includes:sending, by the sending unit in a subframe n, the first data to thesecond communications device, where the subframe n belongs to the xsubframes; and the second resource includes y subframes, where y is apositive integer, and that the receiving unit receives, on the secondresource, the response information of the first data from the secondcommunications device includes: receiving, by the receiving unit in asubframe m, the response information of the first data from the secondcommunications device, where the subframe m belongs to the y subframes,and the subframe m is a subframe, after a subframe n+k, with a minimumsequence number in the y subframes of the second resource, where thesubframe n+k is a k^(th) subframe after the subframe n, k is predefinedor is received by the receiving unit from the network device, and n, m,and k are all non-negative integers.

In a possible design, the subframe m includes a plurality of first timeunits, and that the receiving unit receives, in the subframe m, theresponse information of the first data from the second communicationsdevice includes: receiving, by the receiving unit on one of theplurality of first time units included in the subframe m, the responseinformation of the first data from the second communications device.Therefore, resource utilization efficiency can be improved.

In a possible design, that the receiving unit receives, in the subframem, the response information of the first data from the secondcommunications device includes: receiving, by the receiving unit on somefrequency domain resources in the subframe m, the response informationof the first data from the second communications device. Therefore,resource utilization efficiency can be improved.

In a possible design, the first indication information includes a firstbit map, and the second indication information includes a second bitmap.

According to a third aspect, a response information sending method isprovided. The method includes: receiving, by a second communicationsdevice, first indication information from a network device, where thefirst indication information is used to indicate a first resource fortransmitting first data; receiving, by the second communications deviceon the first resource, the first data from a first communicationsdevice; receiving, by the second communications device, secondindication information from the network device, where the secondindication information is used to indicate a second resource fortransmitting response information of the first data, and the secondresource and the first resource do not include a same resource; andsending, by the second communications device on the second resource, theresponse information of the first data to the first communicationsdevice.

According to this embodiment of this application, the network deviceconfigures, for the first communications device and the secondcommunications device, the second resource that can be used for theresponse information. The first communications device and the secondcommunications device may transmit the response information on thesecond resource, and transmission of the response information isimplemented in V2X communication.

In a possible design, the first resource includes x subframes, where xis a positive integer, and the receiving, by the second communicationsdevice on the first resource, the first data from a first communicationsdevice includes: receiving, by the second communications device in asubframe n, the first data from the first communications device, wherethe subframe n belongs to the x subframes; and the second resourceincludes y subframes, where y is a positive integer, and the sending, bythe second communications device on the second resource, the responseinformation of the first data to the first communications deviceincludes: sending, by the second communications device in a subframe m,the response information of the first data to the first communicationsdevice, where the subframe m belongs to the y subframes, and thesubframe m is a subframe, after a subframe n+k, with a minimum sequencenumber in the y subframes of the second resource, where the subframe n+kis a k^(th) subframe after the subframe n, k is predefined, is receivedby the second communications device from the first communicationsdevice, or is received by the second communications device from thenetwork device, and n, m, and k are all non-negative integers.

In a possible design, the subframe m includes a plurality of first timeunits, and the sending, by the second communications device in asubframe m, the response information of the first data to the firstcommunications device includes: sending, by the second communicationsdevice on one of the plurality of first time units included in thesubframe m, the response information of the first data to the firstcommunications device. Therefore, resource utilization efficiency can beimproved.

In a possible design, the sending, by the second communications devicein a subframe m, the response information of the first data to the firstcommunications device includes: sending, by the second communicationsdevice on some frequency domain resources in the subframe m, theresponse information of the first data to the first communicationsdevice. Therefore, resource utilization efficiency can be improved.

In a possible design, the first indication information includes a firstbit map, and the second indication information includes a second bitmap.

According to a fourth aspect, a second communications device isprovided. The second communications device includes: a receiving unit,configured to receive first indication information from a networkdevice, where the first indication information is used to indicate afirst resource for transmitting first data; the receiving unit isfurther configured to receive, on the first resource, the first datafrom a first communications device; and the receiving unit is furtherconfigured to receive second indication information from the networkdevice, where the second indication information is used to indicate asecond resource for transmitting response information of the first data,and the second resource and the first resource do not include a sameresource; and a sending unit, configured to send, on the secondresource, the response information of the first data to the firstcommunications device.

According to this embodiment of this application, the network deviceconfigures, for the first communications device and the secondcommunications device, the second resource that can be used for theresponse information. The first communications device and the secondcommunications device may transmit the response information on thesecond resource, and transmission of the response information isimplemented in V2X communication.

In a possible design, the first resource includes x subframes, where xis a positive integer, and that the receiving unit receives, on thefirst resource, the first data from the first communications deviceincludes: receiving, by the receiving unit in a subframe n, the firstdata from the first communications device, where the subframe n belongsto the x subframes; and the second resource includes y subframes, wherey is a positive integer, and that the sending unit sends, on the secondresource, the response information of the first data to the firstcommunications device includes: sending, by the sending unit in asubframe m, the response information of the first data to the firstcommunications device, where the subframe m belongs to the y subframes,and the subframe m is a subframe, after a subframe n+k, with a minimumsequence number in the y subframes of the second resource, where thesubframe n+k is a k^(th) subframe after the subframe n, k is predefined,is received by the receiving unit from the first communications device,or is received by the receiving unit from the network device, and n, m,and k are all non-negative integers.

In a possible design, the subframe m includes a plurality of first timeunits, and that the sending unit sends, in the subframe m, the responseinformation of the first data to the first communications deviceincludes: sending, by the sending unit on one of the plurality of firsttime units included in the subframe m, the response information of thefirst data to the first communications device. Therefore, resourceutilization efficiency can be improved.

In a possible design, that the sending unit sends, in the subframe m,the response information of the first data to the first communicationsdevice includes: sending, by the sending unit on some frequency domainresources in the subframe m, the response information of the first datato the first communications device. Therefore, resource utilizationefficiency can be improved.

In a possible design, the first indication information includes a firstbit map, and the second indication information includes a second bitmap.

According to a fifth aspect, a response information transmissionresource indication method is provided. The method includes: sending, bya network device, first indication information to at least onecommunications device, where the first indication information is used toindicate a first resource for transmitting first data between a firstcommunications device and a second communications device, and the firstcommunications device and the second communications device belong to theat least one communications device; and sending, by the network device,second indication information to the at least one communications device,where the second indication information is used to indicate a secondresource for transmitting response information of the first data betweenthe first communications device and the second communications device,and the second resource and the first resource do not include a samesubframe.

According to this embodiment of this application, the network deviceconfigures, for the first communications device and the secondcommunications device, the second resource that can be used for theresponse information. The first communications device and the secondcommunications device may transmit the response information on thesecond resource, and transmission of the response information isimplemented in V2X communication.

In a possible design, the first indication information includes a firstbit map, and the second indication information includes a second bitmap.

According to a sixth aspect, a network device is provided. The networkdevice includes: a sending unit, configured to send first indicationinformation to at least one communications device, where the firstindication information is used to indicate a first resource fortransmitting first data between a first communications device and asecond communications device, and the first communications device andthe second communications device belong to the at least onecommunications device; and the sending unit is further configured tosend second indication information to the at least one communicationsdevice, where the second indication information is used to indicate asecond resource for transmitting response information of the first databetween the first communications device and the second communicationsdevice, and the second resource and the first resource do not include asame subframe.

According to this embodiment of this application, the network deviceconfigures, for the first communications device and the secondcommunications device, the second resource that can be used for theresponse information. The first communications device and the secondcommunications device may transmit the response information on thesecond resource, and transmission of the response information isimplemented in V2X communication.

In a possible design, the first indication information includes a firstbit map, and the second indication information includes a second bitmap.

According to a seventh aspect, an embodiment of this applicationprovides a computer storage medium. The computer storage medium isconfigured to store a computer software instruction used by theforegoing network device, and the computer software instruction includesa program designed for performing the foregoing aspects.

According to an eighth aspect, an embodiment of this applicationprovides a computer storage medium. The computer storage medium isconfigured to store a computer software instruction used by the firstcommunications device or the second communications device, and thecomputer software instruction includes a program designed for performingthe foregoing aspects.

According to a ninth aspect, an embodiment of this application providesa computer program product. The program product stores a computersoftware instruction used by the foregoing access network device, thefirst communications device, or the second communications device, andthe computer software instruction includes a program used to perform thesolutions in the foregoing aspects.

According to a tenth aspect, an embodiment of this application providesa chip, configured to perform the methods in the foregoing aspects. Thechip may include a part having functions of a memory, a processor, atransmitter, a receiver, and/or a transceiver, and the memory stores aninstruction, code, and/or data, to perform the methods in the foregoingaspects.

According to an eleventh aspect, an embodiment of this applicationprovides a system. The system includes the network device, the firstcommunications device, and/or the second communications device in theforegoing aspects.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic architectural diagram of a system according to anembodiment of this application;

FIG. 2 shows a response information transmission method, a firstcommunications device, a second communications device, and a networkdevice according to an embodiment of this application;

FIG. 3 is a schematic diagram of subframes for response informationtransmission according to an embodiment of this application;

FIG. 4 is a schematic diagram of subframes for response informationtransmission according to an embodiment of this application;

FIG. 5 is a schematic time sequence diagram of response informationtransmission according to an embodiment of this application;

FIG. 6 is a schematic time sequence diagram of response informationtransmission according to an embodiment of this application;

FIG. 7 is a schematic diagram of subframes for response informationtransmission according to an embodiment of this application;

FIG. 8 is a schematic diagram of subframes for response informationtransmission according to an embodiment of this application;

FIG. 9 shows a first communications device according to an embodiment ofthis application;

FIG. 10 shows a second communications device according to an embodimentof this application; and

FIG. 11 shows a network device according to an embodiment of thisapplication.

DESCRIPTION OF EMBODIMENTS

In FIG. 1 , a network device sends indication information to a firstcommunications device and a second communications device. The indicationinformation indicates a resource configured by the network device fortransmitting response information between the first communicationsdevice and the second communications device. The first communicationsdevice may determine, through scheduling by a base station or autonomousselection, a resource used to send data, and send, on the resource, thedata to the second communications device. The second communicationsdevice may correctly receive the data, or cannot correctly receive thedata. Then, the second communications device sends, on the resource fortransmitting the response information that is indicated by theindication information, the response information to the firstcommunications device, and the response information is used to feed backa transmission status of the data. The response information may beacknowledgement (ACK) information or negative acknowledgement (NACK)information.

The network device in this application is an apparatus that is deployedin a radio access network and that is configured to provide a wirelesscommunication function for a communications device. The network devicemay include various forms of base stations (BS), such as a macro basestation, a micro base station, a relay node, or an access point. Insystems using different radio access technologies, a device having anetwork device function may have different names. For example, in a 5thgeneration 5G network, the device is a network device; in an LTEnetwork, the device is referred to as an evolved NodeB (eNB or eNodeBfor short); and in a 3rd generation 3G network, the device is referredto as a NodeB. The device is alternatively a road side unit (RSU) in V2Vcommunication, or the network device may be a chip or a system on chip(SOC). For ease of description, in this application, the foregoingapparatus that provides the wireless communication function for thecommunications device is collectively referred to as the network device.

The communications device in this application may include varioushandheld devices having the wireless communication function, forexample, a vehicle-mounted device, a wearable device, a computingdevice, or another processing device connected to a wireless modem, amobile station (MS), a terminal, user equipment (UE), a chip, or an SOC.For ease of description, in this application, the devices mentionedabove are collectively referred to as the communications device.

The following describes the embodiments of this application in moredetail with reference to specific examples by using a network device, afirst communications device, and a second communications device as anexample.

FIG. 2 shows a response information transmission method, a firstcommunications device, a second communications device, a network device,and a system according to an embodiment of this application. As shown inFIG. 9 , the first communications device includes a receiving unit 91and a sending unit 92. The first communications device may furtherinclude a determining unit 93, and the receiving unit 91 and the sendingunit 92 communicate with the determining unit 93. As shown in FIG. 10 ,the second communications device includes a receiving unit 101 and asending unit 102. The second communications device may further include adetermining unit 103, and the receiving unit 101 and the sending unit102 communicate with the determining unit 103. As shown in FIG. 11 , thenetwork device includes a sending unit 111. The network device mayfurther include a determining unit 112 and a receiving unit 113, and thereceiving unit 113 and the sending unit 111 communicate with thedetermining unit 112.

Step 21: The sending unit 111 of the network device sends firstindication information to at least one communications device.Specifically, as shown in FIG. 2 , the network device sends firstindication information to the first communications device and the secondcommunications device. The receiving unit 91 of the first communicationsdevice receives the first indication information from the networkdevice, and the receiving unit 101 of the second communications devicealso receives the first indication information from the network device,where the first indication information is used to indicate a firstresource for transmitting first data. The network device notifies, byusing the first indication information, the first communications deviceand the second communications device of the resource allocated by thenetwork device for V2X communication between the first communicationsdevice and the second communications device, so that the firstcommunications device and the second communications device can performdata transmission on the resource allocated by the network device.

In FIG. 2 , a sequence in which the network device sends the firstindication information to the first communications device and sends thefirst indication information to the second communications device is notlimited. Preferably, the network device sends, in a broadcast manner,the first indication information to the first communications device andthe second communications device, where the first indication informationmay be bit map information, and the first indication information may besent by using radio resource control (RRC) signaling. Specifically, asshown in FIG. 3 , the first indication information is used by thenetwork device to indicate, to a plurality of communications devices,time domain information of the resource allocated by the network devicefor the V2X communication. A length of a bit map shown in FIG. 3 is 8bits, and the bit map is specifically 11000001. The bit map is used toperiodically indicate time domain resources used for V2X communication.For example, the bit map is used to indicate that a subframe 0, asubframe 1, and a subframe 7 can be used as resources that can be usedfor V2X communication in the first period, and in the second period, thebit map indicates that a subframe 8, a subframe 9, and a subframe 15 maybe used as resources that can be used for V2X communication in thesecond period. In other words, the first resource indicated by the firstindication information includes subframes that can be used for V2Xcommunication.

In FIG. 3 , for a subframe used for V2X communication, the networkdevice divides a frequency domain resource into several sub-channels,and each sub-channel includes several resource blocks (RB). The networkdevice indicates, to the communications device by using the indicationinformation, a sequence number of the first resource block of a resourceused for V2X communication. A quantity of resource blocks included ineach sub-channel is nal, and a quantity of sub-channels that can be usedfor V2X communication is N, where nal and N are positive integers.Preferably, the network device may notify, by using the first indicationinformation, the first communications device and the secondcommunications device of the sequence number of the first resource blockof the resource used for the V2X communication resource, nal, and N.Certainly, the network device may alternatively send the foregoinginformation to the first communications device and the secondcommunications device by using other indication information.

Step 22: The sending unit 92 of the first communications device sends,on the first resource indicated by the first indication information, thefirst data to the second communications device, and the receiving unit101 of the second communications device receives, on the first resource,the first data from the first communications device. The first data maybe status information periodically sent by a vehicle to another vehicle,such as location information, speed information, or other statusinformation. The second communications device may learn of statusinformation of the first communications device, and adjust a travelingdirection, a speed, and the like of the second communications devicebased on the status information of the first communications device, andtherefore, travelling safety of the second communications device isimproved. Preferably, the first communications device sends, in abroadcast manner, the first data to the second communications device andanother communications device around the first communications device.

Although the first communications device sends the first data to thesecond communications device, the second communications device maycorrectly receive the first data, or may not correctly receive the firstdata.

Step 23: The sending unit 111 of the network device sends secondindication information to the at least one communications device.Specifically, as shown in FIG. 2 , the network device sends secondindication information to the first communications device and the secondcommunications device. The receiving unit 91 of the first communicationsdevice receives the second indication information from the networkdevice, the receiving unit 101 of the second communications device alsoreceives the second indication information from the network device,where the second indication information is used to indicate a secondresource for transmitting response information of the first data, andthe second resource and the first resource do not include a sameresource.

The second indication information may include bit map information. A bitmap is used to periodically indicate a resource used for responseinformation transmission. As shown in FIG. 4 , a first bit map is11000000, and indicates that subframes used for V2X data transmissionare a subframe 0, a subframe 1, a subframe 8, a subframe 9, a subframe16, a subframe 17, and the like, and that a subframe 2 to a subframe 6and a subframe 10 to a subframe 14 are common subframes. A second bitmap is 00000001, and indicates that subframes used for transmitting theresponse information of the data are a subframe 7, a subframe 15, asubframe 23, and the like. Resources used for response informationtransmission and resources used for V2X data transmission do not includea same resource, in other words, the resources used for responseinformation transmission and the resources used for V2X datatransmission are different resources. Preferably, response informationof V2X data is transmitted in the first subframe that appears after aresource used for transmitting the V2X data. For example, as shown inFIG. 4 , response information of V2X data transmitted in the subframe 0and the subframe 1 is fed back in the subframe 7. Response informationof V2X data transmitted in the subframe 8 and the subframe 9 is fed backin the subframe 15. The response information includes ACK information orNACK information, and the response information does not includeadditional information. For example, the response information does notinclude communications device identification information correspondingto the response information, or does not include data packetidentification information corresponding to the response information.Therefore, a specific rule needs to be preset in a communicationsprotocol, so that the communications device learns of a specific datapacket of a specific communications device to which the responseinformation belongs. For example, the preset rule may be in ascendingorder of subframe numbers and in ascending order of sub-channel numbers.Sub-channels in a subframe with a smaller subframe number are firstmapped to the response information transmission resource, and thensub-channels in a subframe with a larger subframe number are mapped tothe response information transmission resource. For example, in FIG. 4 ,the subframe 0 includes four sub-channels: a sub-channel 1 to asub-channel 4, and the subframe 1 also includes four sub-channels: asub-channel 1 to a sub-channel 4. In this case, an ACK/NACK resource 1is used to feed back response information of the sub-channel 1 in thesubframe 0, an ACK/NACK resource 2 is used to feed back responseinformation of the sub-channel 2 in the subframe 0, an ACK/NACK resource3 is used to feed back response information of the sub-channel 3 in thesubframe 0, an ACK/NACK resource 4 is used to feed back responseinformation of the sub-channel 4 in the subframe 0, an ACK/NACK resource5 is used to feed back response information of the sub-channel 1 of thesub-frame 1, an ACK/NACK resource 6 is used to feed back responseinformation of the sub-channel 2 of the sub-frame 1, an ACK/NACKresource 7 is used to feed back response information of the sub-channel3 of the sub-frame 1, and an ACK/NACK resource 8 is used to feed backresponse information of the sub-channel 4 in the subframe 1. Preferably,a location of the resource used to transmit the ACK/NACK may be afunction of an index of a slot in which data corresponding to theACK/NACK is located and a lowest sub-channel index.

The first resource includes x subframes, where x is a positive integer,and the sending, by the first communications device on the firstresource, the first data to the second communications device includes:sending, by the first communications device in a subframe n, the firstdata to the second communications device, where the subframe n belongsto the x subframes. The second resource includes y subframes, where y isa positive integer, and the receiving, by the first communicationsdevice on the second resource, the response information of the firstdata from the second communications device includes: receiving, by thefirst communications device in a subframe m, the response information ofthe first data from the second communications device, where the subframem belongs to the y subframes, and the subframe m is a subframe, after asubframe n+k, with a smallest sequence number in the y subframes of thesecond resource, where the subframe n+k is a k^(th) subframe after thesubframe n, and n, m, and k are all non-negative integers. If thesubframe n+k is a subframe that belongs to the second resource, aresource used to feed back response information of data transmitted inthe subframe n may be the subframe n+k, or may be a subframe n+k+1.

A value of k may be predefined in a protocol. For example, as shown inFIG. 5 , a first resource includes a subframe 0, a subframe 1, asubframe 4, a subframe 5, a subframe 6, and the like, a second resourceincludes a subframe 3, a subframe 7, and the like, and that a value of kis 2 is preset in the protocol. For the subframe 0, a value of n is 0,so that a value of n+k is 2. In this case, a subframe, after a subframe2, with a smallest sequence number in the second resource is thesubframe 3, so that response information of data transmitted in thesubframe 0 is fed back in the subframe 3. Similarly, responseinformation of data transmitted in the subframe 1 is fed back in thesubframe 3, response information of data transmitted in the subframe 4is fed back in the subframe 7, and the rest may be deduced by analogy.

A value of k may alternatively be semi-statically configured ordynamically configured. For example, the value of k may be sent by thenetwork device to the first communications device or the secondcommunications device, or the value of k may be sent by the networkdevice to the first communications device and then sent by the firstcommunications device to the second communications device. The value ofk may be independently configured for different subframes, may beconfigured for a subframe in a period, or may be configured to be thesame for all subframes. As shown in FIG. 6 , a first resource includes asubframe 0, a subframe 1, a subframe 4, a subframe 5, a subframe 6, andthe like, a second resource includes a subframe 3, a subframe 7, and thelike. Therefore, for the subframe 0, a value of n is 0, so that a valueof n+k is 2. Therefore, a subframe, after a subframe 2, with a smallestsequence number in the second resource is the subframe 3, so thatresponse information of data transmitted in the subframe 0 is fed backin the subframe 3. For the subframe 1, a value of n is 1, a value of kis 4, so that a value of n+k is 5. Therefore, a subframe, after thesubframe 5, with a smallest sequence number in the second resource isthe subframe 7, so that response information of data transmitted in thesubframe 1 is fed back in the subframe 7. For the subframe 4, a value ofn is 4, a value of k is 3, so that a value of n+k is 7. Therefore, asubframe, after the subframe 7, with a smallest sequence number in thesecond resource is the subframe 7, so that response information of datatransmitted in the subframe 4 is fed back in the subframe 7. The restmay be deduced by analogy.

Optionally, the subframe m includes a plurality of first time units, andthe receiving, by the first communications device in the subframe m, theresponse information of the first data from the second communicationsdevice includes: receiving, by the first communications device on one ofthe plurality of first time units included in the subframe m, theresponse information of the first data from the second communicationsdevice. Preferably, the first time unit may be a slot, a mini-slot, or asymbol. Specifically, a specific first time unit or several specificfirst time units that are in the plurality of first time units includedin the subframe m and that are used for response informationtransmission may be predefined by a protocol, or may be semi-staticallyor dynamically configured by the network device. For example, as shownin FIG. 7 , a first bit map is 10110111, and therefore, a subframe 0, asubframe 2, a subframe 3, a subframe 5, a subframe 6, a subframe 7, andthe like are a first resource used for V2X data transmission. A secondbit map is 00010001, and therefore, a subframe 3, a subframe 7, and thelike are a second resource used for response information transmission.It can be learned that the subframe 3, the subframe 7, and the like areused for both V2X data transmission and response informationtransmission. A mini-slot 1 in the subframe 3 is used for datatransmission, and a mini-slot 2 in the subframe 3 is used for responseinformation transmission. If response information of data transmitted inthe subframe 0, the subframe 2, and the mini-slot 1 in the subframe 3 isfed back in the mini-slot 2 in the subframe 3, and when the subframe 0and the subframe 1 each include two sub-channels and the mini-slot 1 inthe subframe 3 includes only one sub-channel, a response informationresource 1 is used to feed back response information of data transmittedon a sub-channel 1 in the subframe 0, a response information resource 2is used to feed back response information of data transmitted on asub-channel 2 in the subframe 0, a response information resource 3 isused to feed back response information of data transmitted on asub-channel 1 in the subframe 2, a response information resource 4 isused to feed back response information of data transmitted on asub-channel 2 in the subframe 2, and a response information resource 5is used to feed back response information of data transmitted on asub-channel 1 in the mini-slot 1 in the subframe 3. Therefore, resourceutilization efficiency can be improved.

Optionally, the receiving, by the first communications device in thesubframe m, the response information of the first data from the secondcommunications device includes: receiving, by the first communicationsdevice on some frequency domain resources in the subframe m, theresponse information of the first data from the second communicationsdevice. Specifically, a specific frequency domain resource or severalspecific frequency domain resources that are in the plurality offrequency domain resources included in the subframe m and that are usedfor response information transmission may be predefined by a protocol,or may be semi-statically or dynamically configured by the networkdevice. For example, as shown in FIG. 8 , a first bit map is 10110111,and therefore, a subframe 0, a subframe 2, a subframe 3, a subframe 5, asubframe 6, a subframe 7, and the like are a first resource used for V2Xdata transmission. A second bit map is 00010001, and therefore, asubframe 3, a subframe 7, and the like are a second resource used forresponse information transmission. It can be learned that the subframe3, the subframe 7, and the like are used for both V2X data transmissionand response information transmission. In FIG. 8 , in the subframe 3,only some frequency domain resources are used for response informationtransmission. In the subframe 3 or the subframe 7, a frequency domainresource may be divided into several frequency domain units. Forexample, a frequency domain unit may be a subcarrier or a sub-channel.In this case, one or more frequency domain units of the frequency domainresource are used for response information transmission, and a remainingfrequency domain unit may be used for data transmission. Therefore,resource utilization efficiency can be improved.

Preferably, the first communications device may dynamically notify, byusing control signaling, the second communications device whether aresponse information feedback needs to be performed on the data sent bythe first communications device to the second communications device. Ifthe response information needs to be fed back, the method in step 23 isused, and the second communications device feeds back the responseinformation to the first communications device. If the responseinformation does not need to be fed back, a resource used to feed backthe response information of the data is released, to be used for otherV2X data communication.

Step 24: The receiving unit 91 of the first communications devicereceives, on the second resource, the response information of the firstdata from the second communications device, and the sending unit 102 ofthe second communications device sends, on the second resource, theresponse information of the first data to the second communicationsdevice. The response information includes ACK information or NACKinformation. When the first communications device receives the ACKinformation from the second communications device, the firstcommunications device no longer sends the first data to the secondcommunications device, and therefore, communication resources are saved.When the first communications device receives the NACK information fromthe second communications device, the first communications device sendsthe first data to the second communications device again, and therefore,reliability of receiving the first data by the second communicationsdevice is improved, and reliable transmission of V2X data betweendifferent communications devices is ensured.

The receiving unit 91 included in the first communications device may bereplaced by a receiver, the determining unit 93 may be replaced by aprocessor, and the sending unit 92 may be replaced by a transmitter. Thesending unit 102 included in the second communications device may bereplaced by a transmitter, the determining unit 103 may be replaced by aprocessor, and the receiving unit 101 may be replaced by a receiver. Thesending unit 111 included in the network device may be replaced by atransmitter, the determining unit 112 may be replaced by a processor,and the receiving unit 113 may be replaced by a receiver. Alternatively,the first communications device, the second communications device, orthe network device may be a chip or a system on chip, to complete themethod shown in the embodiment of FIG. 2 .

According to this embodiment of this application, the network deviceconfigures, for the first communications device and the secondcommunications device, the second resource that can be used for theresponse information. The first communications device and the secondcommunications device may transmit the response information on thesecond resource, and transmission of the response information isimplemented in V2X communication.

In the several embodiments provided in this application, it should beunderstood that the disclosed system, apparatus, and method may beimplemented in other manners. For example, the described apparatusembodiment is merely an example. For example, the unit division ismerely logical function division and may be other division in actualimplementation. For example, a plurality of units or components may becombined or integrated into another system, or some features may beignored or not performed. In addition, the displayed or discussed mutualcouplings or direct couplings or communication connections may beimplemented by using some interfaces. The indirect couplings orcommunication connections between the apparatuses or units may beimplemented in electronic, mechanical, or other forms.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,may be located in one position, or may be distributed on a plurality ofnetwork units. Some or all of the units may be selected based on actualrequirements to achieve the objectives of the solutions of theembodiments.

In addition, functional units in the embodiments of this application maybe integrated into one processing unit, or each of the units may existalone physically, or two or more units are integrated into one unit. Theintegrated unit may be implemented in a form of hardware, or may beimplemented in a form of a software functional unit.

When the integrated unit is implemented in the form of a softwarefunctional unit and sold or used as an independent product, theintegrated unit may be stored in a computer-readable storage medium.Based on such an understanding, the technical solutions of thisapplication essentially, or the part contributing to the prior art, orall or some of the technical solutions may be implemented in a form of asoftware product. The software product is stored in a storage medium andincludes several instructions for instructing a computer device (whichmay be a personal computer, a server, or a network device) to performall or some of the steps of the methods described in the embodiments ofthis application. The foregoing storage medium includes: any medium thatcan store program code, such as a USB flash drive, a removable harddisk, a read-only memory (ROM), a random access memory (RAM), a magneticdisk, or an optical disc.

What is claimed is:
 1. A communication method, comprising: receiving, bya first communications device, first indication information from anetwork device, wherein the first indication information indicates afirst resource for sidelink communication, the first resource comprisesx subframes, and x is a positive integer larger than 1; sending, by thefirst communications device, in a subframe n, first data to a secondcommunications device, wherein the subframe n belongs to the xsubframes; receiving, by the first communications device, secondindication information from the network device, wherein the secondindication information is used to determine a second resource fortransmitting feedback information, wherein the second resource comprisesy subframes, y is a positive integer, and the y subframes belong to thex subframes; and receiving, by the first communications device in asubframe m, feedback information of the first data from the secondcommunications device, wherein the subframe m belongs to the ysubframes.
 2. The communication method according to claim 1, wherein:the subframe m is a subframe that is after a subframe n+k and with aminimum sequence number in the y subframes, wherein the subframe n+k isa k^(th) subframe after the subframe n, wherein k is predefined or isreceived by the first communications device from the network device, andwherein n, m, and k are all non-negative integers.
 3. The communicationmethod according to claim 1, wherein: the subframe m comprises aplurality of first time units; and the receiving, by the firstcommunications device in the subframe m, the feedback information of thefirst data from the second communications device comprises: receiving,on one of the plurality of first time units comprised in the subframe m,the feedback information of the first data from the secondcommunications device.
 4. The communication method according to claim 3,wherein: a first time unit is a slot, a mini-slot, or a symbol.
 5. Thecommunication method according to claim 3, wherein: there are Psubframes between two adjacent subframes in the y subframes; a number ofresources for transmitting feedback information and that are containedin the subframe m is a first value; and the first value is equal to asum of a number of subchannels included in at least one first symbol onthe subframe m and a number of subchannels included in subframes fortransmitting data transmission in P adjacent subframes before thesubframe m.
 6. The communication method according to claim 1, wherein:the first indication information comprises a first bit map; and thesecond indication information comprises a second bit map.
 7. Thecommunication method according to claim 1, wherein at least one firstsymbol in each of the y subframes is used to transmit data, at least onesecond symbol in each of the y subframes is used to transmit feedbackinformation, the at least one first symbol and the at least one secondsymbol comprises different resources.
 8. The communication methodaccording to claim 1, wherein: a location of resource for transmittingthe feedback information of the first data is a function of an index ofa slot in which the first data located and a lowest sub-channel index inwhich the first data located.
 9. A first communications device,comprising: at least one processor; and one or more memories coupled tothe at least one processor and storing instructions for execution by theat least one processor to: receive first indication information from anetwork device, wherein the first indication information indicates afirst resource for sidelink communication, the first resource comprisesx subframes, and x is a positive integer larger than 1; send, in asubframe n, first data to a second communications device, wherein thesubframe n belongs to the x subframes; receive second indicationinformation from the network device, wherein the second indicationinformation is used to determine a second resource for transmittingfeedback information, wherein the second resource comprises y subframes,y is a positive integer, and the y subframes belong to the x subframes;and receive, in a subframe m, feedback information of the first datafrom the second communications device, wherein the subframe m belongs tothe y subframes.
 10. The first communications device according to claim9, wherein: the subframe m is a subframe that is after a subframe n+kand with a minimum sequence number in the y subframes, wherein thesubframe n+k is a kth subframe after the subframe n, wherein k ispredefined or is received by the first communications device from thenetwork device, and wherein n, m, and k are all non-negative integers.11. The first communications device according to claim 9, wherein: thesubframe m comprises a plurality of first time units; and receiving, inthe subframe m, the feedback information of the first data from thesecond communications device comprises: receiving, on one of theplurality of first time units comprised in the subframe m, the feedbackinformation of the first data from the second communications device. 12.The first communications device according to claim 11, wherein at leastone first symbol in each of the y subframes is used to transmit data, atleast one second symbol in each of the y subframes is used to transmitfeedback information, the at least one first symbol and the at least onesecond symbol comprises different resources.
 13. The firstcommunications device according to claim 11, wherein: a first time unitis a slot, a mini-slot, or a symbol.
 14. The first communications deviceaccording to claim 11, wherein: there are P subframes between twoadjacent subframes in the y subframes; a number of resources fortransmitting feedback information and that are contained in the subframem is a first value; and the first value is equal to a sum of a number ofsubchannels included in at least one first symbol on the subframe m anda number of subchannels included in subframes for transmitting datatransmission in P adjacent subframes before the subframe m.
 15. Thefirst communications device according to claim 9, wherein: the firstindication information comprises a first bit map; and the secondindication information comprises a second bit map.
 16. The firstcommunications device according to claim 9, wherein: a location ofresource for transmitting the feedback information of the first data isa function of an index of a slot in which the first data located and alowest sub-channel index in which the first data located.
 17. A secondcommunications device, comprising: at least one processor; and one ormore memories coupled to the at least one processor and storinginstructions for execution by the at least one processor to: receivefirst indication information from a network device, wherein the firstindication information indicates a first resource for sidelinkcommunication, the first resource comprises x subframes, and x is apositive integer larger than 1; receive, in a subframe n, first datafrom a first communications device; receive second indicationinformation from the network device, wherein the second indicationinformation is used to determine a second resource for transmittingfeedback information, wherein the second resource comprises y subframes,y is a positive integer, and the y subframes belong to the x subframes;and send, in a subframe m, feedback information of the first data to thefirst communications device.
 18. The second communications deviceaccording to claim 17, wherein: the subframe m belongs to the ysubframes, the subframe m is a subframe that is after a subframe n+k andwith a minimum sequence number in the y subframes of the secondresource, wherein the subframe n+k is a kth subframe after the subframen, wherein k is predefined or is received by the first communicationsdevice from the network device, and wherein n, m, and k are allnon-negative integers.
 19. The second communications device according toclaim 17, wherein: the subframe m comprises a plurality of first timeunits; and receiving, by the first communications device in the subframem, the feedback information of the first data from the secondcommunications device comprises: receiving, on one of the plurality offirst time units comprised in the subframe m, the feedback informationof the first data from the second communications device.
 20. The secondcommunications device according to claim 17, wherein: the firstindication information comprises a first bit map; and the secondindication information comprises a second bit map.